This invention relates generally to safety systems; more particularly, this invention is concerned with an escape system for safely and rapidly lowering personnel to a safe level (e.g., the ground) from a relatively high point. Still more particularly, this invention is directed to an escape system for lowering personnel to the ground or deck level from an elevated location such as the racking board level, of a drilling rig, or similar tower-like structure.
In oil drilling rigs and in particular, offshore drilling rigs, situations arise where the personnel on the rig must be removed from the derrick immediately to avoid injury due to blowout or other imminent danger. For example, where a man is working on the racking level, putting the drilling pipe in order, there presently exists no quick and efficient way for him to be removed from that level should a blowout occur.
Methods have been developed for transporting personnel off of drilling platforms where fire or other hazards exist. However, these have typically been mechanisms which do not operate with the urgency required for immediate displacement from a danger zone. An example of this is U.S. Pat. No. 3,880,254, where there is shown a boom which is maintained in a biased position to take advantage of gravity or bouyancy to pivot the boom from the rig. But, when released, the boom rotates into the water adjacent an offshore drilling platform. A lifeline connected to the boom head allows personnel desiring to escape from the platform to simply slide down the lifeline to the head at the end of the boom. This type of mechanism does not actually move personnel away from a danger zone but simply provides a path and a platform at the end of the path to which personnel may eventually escape. Furthermore, it does not provide an effective means for removing personnel from the racking board level, where often the danger is most imminent, in a quick and efficient manner.
In a blow-out situation there is usually the danger of fire. In addition to the danger from flying objects, such as rocks, pipe lengths, etc., and high pressure fluid streams erupting from the hole, all of which can cause bodily injury to personnel, there is the real danger of a spark igniting the oil or gas spewing out to heights which may be greater than the total height of the rig itself. It is, therefore, imperative, not only to provide a means for permitting rapid escape from, say, the racking level, but to protect personnel as well from flying objects and/or fire during such escape.
In certain offshore environments, such as the North Sea or Straits of Magellan, sea conditions are so harsh that an escape system which terminates at a buoy in the water (see. e/g., the aforenamed U.S. Pat. No. 3,880,254), results in an escape route which is akin to "jumping out of the frying pan into the fire." It is therefore, desirable to provide an escape system which terminates on the deck of the rig such that personnel using the escape system will not be exposed to further injury upon impact. This requires a system in which descent conditions are carefully controlled.
It is an object of the invention to overcome the inefficiencies which have existed in safety systems for drilling rigs to deliver personnel from a dangerous position to a safe position remote from the drilling rig derrick.
It is a further object to deliver those personnel working on the derrick of an oil drilling rig, and in particular those drilling rigs used for offshore drilling, quickly and efficiently from the area of the derrick on which they are working to a safe position remote from the derrick on the platform of the drilling rig.
It is still another object of the invention to provide a personnel capsule located adjacent the racking board level for allowing personnel at that level to be removed from the derrick immediately to avoid injury due to blow-out or other imminent danger. The capsule is integrated with a system for releasing the capsule from its position adjacent the racking board level and moving it quickly to a position on the platform of the drilling rig sufficiently remote from the racking board level to avoid any danger which exists in the vicinity of the derrick.
It is another object to provide an assembly for pivoting a personnel capsule away from the derrick of an oil drilling rig and lowering that capsule to a predetermined safe position on the platform of the rig remote from the derrick to provide a means for quickly and efficiently removing personnel away from imminient danger.
Another object of the invention is to control the rate at which a capsule or other personnel carrier is moved away from an oil derrick when personnel on the derrick are being delivered to a position remote from the derrick to avoid injury as a result of a blow-out or other imminent danger.
It is still another object to move a personnel carrier away from an oil derrick and lower the carrier to a platform at a safe position remote from the derrick at a controlled rate of speed.
It is a further object to include a release mechanism operable from within a capsule located adjacent the oil derrick of an oil drilling rig for releasing the capsule from that position adjacent the derrick for allowing the capsule to be moved quickly away from the derrick and delivered to a position sufficiently remote from the derrick to avoid injury which may occur as a result of blowout or other dangerous situations.
It is also an object to incorporate a pneumatic system for actuating a release mechanism which is operable from within a personnel capsule located adjacent the oil derrick of an oil drilling rig for releasing the capsule from the derrick.
It is a further object of the invention to provide a unique linkage system used in conjunction with a capsule or other personnel carrier and the structure connecting the capsule to a means for delivering the capsule from a position adjacent the oil derrick to a remote position away from the derrick to avoid injury to personnel therein. The linkage system is one which allows for some movement of the connecting structure once the capsule has been deposited in a predetermined position without damage to the capsule itself.
It is also an object to control the pendulum effect on the capsule as it is being lowered to prevent the capsule from inadvertently swinging back into the derrick during descent.
These and other objects will become more apparent from the detailed description of the preferred embodiment and the claims which follow hereinafter.